Receiver for heat signs



Aug. 16, 1927. R. MECHAU RECEIVER FOR HEAT SIGNS Filed Aug. 13. 1921 Fig. 4

Patented Aug. 16, 1927.

UNITED STATES PATENT OFFICE.

ROBERT MECHAU, OE JENA, GERMANY, ASSIGNOR To THE FIRM 0F CARL ZEISS, OF JENA, GERMANY.

Application filed August 13, 1921, Serial No perature evoke alterations in the intensity of an electric current passing through it.

These appliances in combination with a current indicator which is to be connected with the heat-sensitive device are intended to indicate changes in temperature which arise in certain places within the field ot' the collective system. Such changes in temperature may for instance be purposely evoked through giving secret signals by means ofheat waves, or they may for instance arise by the source of heat, say the warm funnel of a ship, coming within the field of the collective system. In appliances of this kind the heat-sensitive devices chiefly consist of thermo-elements, thermo-piles, or bolometers. When using a bolometric wire, as a rule a second such wire, of the same form, was arranged in the vicinity of the first, outside the range of the rays emanating from the collectiye system, which second wire was so located 1n the bridge connection containing the first bolometric wire and the current indicator as to influencing the latter in the opposite sense to the first wire, in order to thereby compensate variations in temperature arising in the vicinity of the appllance.

According to the invention, in addition to any desired heat-sensitive device which is used, a second such device of the same construction as the first is disposed in the focal plane of the collective system,in the vicinity of the first device, which entails the advantage that this second device permits of compensating the effect of heat givmg, or heat absorbing bodies which are undesirably situated within the field of the collective system, for instance the influence of the sky, or clouds, etc., since, as a rule these bodies act upon both heat-sensitive devices. The presence of the second device W111, on the other hand, as a rule not influence the indication of the rays the existence of which is to be proved, since these rays will emanate from comparatively small bodies, as for mstance the transmitter of a. signalling device, so that these ra s will onlyact upon the device which is disposed in the focus of the collective system. i

In order to be able ,in each case to adapt RECEIVER FOR HEAT SIGNS.

. 492,135, and in Germany November 25, 1916.

the position of the two heat-senative devices to the position of the bodies sending out the undersired rays, so that the two devices are as well as possible radiated upon in the desired manner, both devices are suitably attached to a common body which is rotatable about the axis of the collective system.

In the annexed drawing a constructional example of an appliance according to the invention is shown. Fig 1 is a cross-section on line 1 1 of Fig. 2. Fig. 2 is partly a side view and partly a section in the direction of the optical axis of the appliance.

In a casing a is disposed a concave metallic mirror b, and, on a column 0 a body d, which latter is rotatable in a collar 0 about the axis XX of the concave mirror and contains a hollow space, which at the side facing the mirror I) is closed up by a quartzplate 6. In the hollow space a vacuum has been produced, and two interconnected bolometric wires 1 and f are disposed therein, which are parallel to one another, their joint being connected, so as to be conductive, to a binding-screw g and their free ends each to a binding-screw The two wires f and f form two neighbouring branches of a VVheatstone bridge, the two other branches ofthe latter being formed by the resistances h and h The bridge connection, which is supplied from a battery 6 with electric current, contains as an indicating device a galvanometer G. In ad-' dition, the arrangement has been so made that the centre of the bolometric wire f coincides with the focal point of the mirror 6, and that the bolometric wire f has a certain distance from the said focal point.

I claim: y

1. The combination with a receiver for heat signals, comprising a casing having an aperture therein, a collective optical system fixed relatively to the aperture and two heat sensitive devices, both said devices being located in the said casing in the focal plane of the said system near each other, and one of the same coinciding with the focal point of the said s stem, of a source of current, a

current in icator and means connecting both said devices and the current indicator in such a manner that one of the devices influences the current indicator in the op-.

posite sense to the other. 2. The combination with a receiver for X heat signals, comprising a casing having an aperture therein, a collective optical system fixed relativel to the aperture, a holder fitted within t e casing rotatably about the 5 axis of the said system, and two heat sensitive-devices fixed at the said holder, both said devices being located in the said casing in the focal plane of the said system near each other, and one of the same coinciding with the focal point of the said system, of a source of current, a current indicator and means connecting both said devices and the current indicator in such a manner that one of the devices influences the current indicator in the opposite sense to the other.

ROBERT MECHAU. 

